Bale movers of various configurations are well known in the art. For example, U.S. Pat. No. 4,564,325 to Ackerman describes a bale-lifting device for use with flat-bed trucks. The device includes a pair of arms that is pivotable longitudinally with respect to the length of the truck to move a bale onto the truck bed or to lower the bale from the bed to the ground. The arms are also pivotable transversely toward one another to pinch the bale therebetween for lifting. Attached to each of the arms is a respective spinner which extends inwardly from the respective arm toward a bale captured between the arms and which forms the primary point of contact between the arm and the bale. The spinners each include an axle rotatably mounted to the respective arm in an orientation perpendicular to the arm and a plate fixedly mounted to the axle in an orientation perpendicular to the arm. The plates bear against the end of the bale and hold the bale in a position to rotate about the axles. The spinners are used during unrolling of the bale for feeding and provide an axis of rotation for the bale.
A problem occurs if the spinners are not properly aligned with the axis of the bale during unrolling. This can cause the bale not to rotate properly and to bind or wobble during unrolling results in the hay not being distributed evenly. Misalignment of the spinners with the bale is often due to the angle between the spinner axle and the respective arm not being correct for the length of the bale.
U.S. Pat. No. 6,099,228 to Krogmann teaches that the spinners can be mounted at an oblique angle to the arms, the angle being selected to align the axis of the spinner with axis of the bale so that the bale will unroll effectively, and suggests that the preferred angle between the arm and the spinner axis is 130 degrees. This arrangement works reasonably well if the bales are of uniform length and if that length is appropriate for the bale mover.
Ranchers feeding hay, however, often encounter variation in the lengths of bales. This variation can be due to acquiring hay from different sources using different equipment to bale the hay or even due to weathering of the bales during storage. It would, therefore, be preferable to provide a bale moving apparatus with spinners which self-adjust to variations in the size of the bales to provide a proper axis of rotation for unrolling the bales, no matter the length of the bale.